The Constitution was made to guard the people against the dangers of good intentions." --American Statesman Daniel Webster (1782-1852)

Friday, September 18, 2020

Tunnel Rats and the tunnels in Vietnam.

 Yesterdays Post got me going down the Rabbit hole again and I decided to do more research in to the Tunnel system.  I had touched upon it yesterday and I decided to explore a bit farther and found more information on the Tunnel system.

I clipped this page from This Source

Click to enlarge

"Bill" an Aussie tunnel rat emerging from a tunnel. Click photo to enlarge. Note the "Australia" badge and the name written on the bush hat. Photo from Vietnam Remembered.

Unofficial motto 

"Non gratum anus rodentum" 

"Not worth a rat's arse" 

or alternatively

"Couldn't Give a Rat's Arse"

This diagram is of a smaller local tunnel system. See  VC Tunnels for it's big brother
Tools of trade for a Tunnel Rat

Knife of type that would be carried


Colt .45 Auto (above)

Smith & Wesson .38 (lower)


Friday 7th of January 1966. The 1st Battalion of the 28th Infantry, itself part of the 3rd Brigade of the 1st Inf Div - "The Big Red One"- was engaged in operation "Crimp". The first search and destroy sweep into the VC held area's Northwest of Saigon. Operation "Crimp" was intended to be a massive strike against the VC in South Vietnam; in and around the Ho Bo woods just west of the Iron triangle.

Even as the men from the 1st Batt 28th Inf touched down on LZ (landing zone) "Jack" they could see their comrades in the 1st Batt 16th Inf were already in trouble and engaging the enemy in small fire fights. The men quickly de-assed their helicopters and moved into the nearby tree line hoping to find, engage, and destroy the VC that had been harassing the soldiers of the 16th Inf.

Just inside the tree line at the edge of a rubber plantation, the men of the 28th discovered a large trench - but no enemy. Where had they gone? How could the VC who had been firing at the men of the 16th Inf just disappear apparently into thin air? As the Batt moved forward it began to find large caches of rice, and enough food to feed a Regiment. As the operation continued, over the next couple of days foxholes, trenches, and caves were discovered. Still no enemy were being engaged in running fire fights, or surrendering, and all the time US casualties were mounting through sustained enemy sniper fire.

By the 10th of January the 28th had reached the banks of the Saigon river. So far during the 3 days of the operation only a couple of brief glimpses of the enemy had been seen. Late in the afternoon of the 10th word came through via the radio that elements of the 173rd Airborne Brigade and the Aussies to the north had made contact with the VC and - found tunnels.

1st Battalion, Royal Australian Regiment, left South Vietnam, having completed almost a full year of combat duty. In leaving, the "diggers" could point with pride to a creditable performance during their stay, highlighted by participation in no fewer than nineteen major operations. Of particular note was an operation conducted in January 1966 which resulted in one of the biggest intelligence coups of the war up to that time. During a sweep of the so-called Iron Triangle, an area near Saigon heavily fortified and controlled by the Viet Cong, the Australian unit discovered a vast complex of tunnels, dug 60 feet deep in some places, which turned out to be a Viet Cong headquarters. In addition to capturing five new Chinese Communist anti-aircraft guns, the Australians discovered 6,000 documents, many revealing names and locations of Viet Cong agents. (from American Report)

The next day the 11th of January the 28th began to retrace it's foot steps. It had finally dawned on the Battalion Commander LTC Robert Haldane what had happened - they had literally walked right over the VC! Searches were begun for the tunnel entrances but nothing much was discovered. By now hot and tired, and waiting for further instructions some of the GIs began to sit down for a quick rest.

Sergeant Stewart Green did the same, but only momentarily, as he suddenly leap to his feet cursing that something had bitten him on the ass. Thinking he'd been stung by a scorpion, or worse, bitten by a snake, Green searched through the layer of dead leaves that covered the area looking for the creature that bitten him. Only to discover it was a nail sticking up from the ground. Upon further careful inspection it was discovered that the nail was part of a small wooden trap door - Haldane's men had found their first tunnel!


Originally the tunnels were started during the war against the French, but which were rapidly expanded upon when the American's arrived. They were constructed by volunteer(!) village labourers using simple hoe's and baskets. The Laterite clay in which the tunnels were dug has a dull reddish appearance and dries rock hard during the dry season. During the wet season it is very soft and much easier to work. Because of the very nature of the Laterite clay's ability to dry rock hard it made a very good (if a somewhat difficult substance to work) soil in which to carve out a tunnel. 

The passages themselves were not cut in dead straight lines, rather they were made with corners that had between a 60 - degree and a 120 - degree angle to them. In other words the corners were constructed with no less than a 60 - degree angle and no more than a 120 - degree angle. This made shooting in a straight line impossible, and helped to deflect explosive blasts from grenades that might be thrown down.

The tunnel systems (where the water table permitted) had several levels, each level was separated by a watertight trap door which would seal the rest of the system against gas, flooding, etc. The trap doors themselves were virtually undetectable and could fool a person into believing that the tunnel finished in a dead end, when in reality it led into a huge system of other passages. These passages would in turn lead to underground ammo dumps, kitchens, air raid shelters, hospitals, store rooms, workshops, latrines, and even theatres for the performances of political plays.

All the tunnel systems had smaller thin (drain pipe sized) ventilation shafts leading from the surface down to the 1st level. These vents were constructed with an oblique angle so as to prevent the monsoon rains flooding the system. Vents were placed so as to face east and the light of a new day, whilst others were placed toward the wind so as to provide a constant cooling draught. Despite these efforts the tunnels were still hot, dark, and claustrophobic, even at the best of times.

The VC also dragged the bodies of their dead comrades underground in order to inter them in temporary graves when it became impossible to bury them above ground due to the presence of American/Australian troops. Once they had been dragged underground they were buried in the foetus position in the tunnel walls and covered with a thin layer of clay.

(an underground man)

The leading scout raised his arm in the village of Long Phuoc
He'd found another tunnel, but who'd go down to look?
The corporal passed the word back, it went back far behind
To let his platoon commander know of his recent find

Then along came this soldier, with mud from head to toe
"Where's the tunnel entrance?" was all he wanted to know
When they showed the soldier, he quickly looked around
And before you could stop him, he'd gone underground

Now he'd been searching on his gut, all that day I bet
Look out for booby traps that good ol' Charlie sets
Then he found the wire, stretched out taut and thin
But he deloused that booby trap, with a safety pin

Then he found the weapons leaning on the wall
There was no disputing he'd found a real big haul
When he finally surfaced, wearing a big grin
He proudly showed the Diggers what he'd found within

Now he'd like to sit down, and roll himself a smoke
But he's been called up forward, by another bloke
So when you see that hat badge, that's like a bursting shell
Remember that this fellow has crawled half way through to hell

And if he's in a bar mate, you buy that bloke a beer
Because Sir, you're drinking with an Aussie Engineer


Originally called "Tunnel Runners" by the 25th Inf Div, and "Ferrets" by the Australian Army, the term "Tunnel Rat" soon became their official accepted name. The US Army soon realized that trying to destroy the tunnels was a short-sighted policy that wasn't going to work. Moreover this was also a loss as the underground networks could yield vital intelligence on the VC in the form of plans and documents.

A chemical officer of the 1st Inf Div, Capt Herbert Thornton a Southerner, was charged with setting up the first tunnel team.

The kind of man that Thornton sought for his tunnel team had to be a special breed. He had to have an even temperament, an inquisitive mind, a lot of common sense (in order to know what to touch and what not to), and to be exceptionally brave.

All of Thornton's men were volunteers, most (not all) were small men of slight build who could squeeze through the tight trap doors and crawl along the narrow passages with relative ease. 

  • No dead tunnel rats were left in a tunnel, dead or wounded they were all dragged out with commo wire, ropes, or by a comrade using a fireman's crawl. 

It was a very stressful, nerve racking job, pushing the rat's mental state to its limits. Crawling through narrow, pitch black tunnels, sometimes for hours looking for a heavily armed enemy who would if he got the drop on you not hesitate to kill you. Occasionally under the strain a mans nerves would break and he'd be dragged from the tunnel screaming and crying. Once this happened he would never be allowed down a tunnel again.

If going down into a tunnel posed a threat, then coming up again could be just as dangerous. Upon emerging from a tunnel a rat would often whistle "Dixie" just to let the troops on the surface know he was on their side. A little guy stripped to the waist and covered in dirt could easily be mistaken (particularly if he was oriental looking) for a VC and shot by his own side.


Going down into a tunnel system was a very risky business fraught with danger. Usually armed only with a pistol or a knife and a flashlight. The tunnel rat would descend into a pitch black, claustrophobic, dank hell, to play a deadly game of hide and seek with the enemy. Carefully probing the floor, sides and roofs of the tunnels became second nature to the tunnel rat as he gently inched and probed his way along. Feeling for wires or tree roots that didn't quite feel right, knowing that anyone of them could detonate a booby trap and blow him to smithereens.

Tunnel entrances were sometimes mined or covered by concealed firing positions. On other occasions an entrance would drop into a punji stake pit which would be covered by two rifle men, one either side. Another way in which the unsuspecting tunnel rat could meet his death was by garrotting him or cutting his throat as he came up through a connecting trapdoor. Besides the booby traps the tunnels also held other nasty surprises. Living along side the VC was a whole plethora of animals which had also made their homes in the dark confines of the tunnels. Bats (the cave dwelling nectar eating bat and the black bearded tomb bat) would use the tunnels as a roosting ground during the daylight hours. 

A tunnel rat crawling through a tight tunnel would wake them from their rest causing them to fly right at him, getting tangled in his hair and running and crawling all over him. Snakes were also encountered underground. Two of the most deadly being the bamboo viper and the Krait. Sometimes the VC would deliberately tether a snake in a tunnel to use it as a sort of natural booby trap.

Scorpions were also used as booby traps, the VC would take boxes of them into the tunnels. The box would be rigged with a trip wire, the tunnel rat tripped the wire and the scorpions would fall on him stinging him in the process. Being stripped to the waist and slowly crawling along on their stomachs also exposed the rats to bites from fire ants that inhabited the underground labyrinths. Other nasties to be encountered in the tunnels were real rats, and spiders like the Giant Crab Spider. Sometimes whole chambers were crawling with a thick black mass of tiny spiders the size of a thumb nail, giving the illusion that the walls were moving!


It was soon discovered early on that to fight in the tunnels the tunnel rat had to do away with most of the infantry mans basic load. In fact the total lack of equipment carried by a rat was a distinct advantage, which greatly increased his chances of survival. The basic tools of the tunnel rat were the knife, the pistol, and a flashlight.

Knife of type that would be carried


Colt .45 Auto

Smith & Wesson .38

The pistols that were carried by the tunnel rats were varied, the .38 Smith and Wesson was a favourite. Other tunnel rats procured their own personal firearms to suit their own needs. One of these was Master Sgt Flo Rivera who acquired and used a 9mm German Luger. The one weapon everyone agreed about was the Colt .45. It was too big, with a silencer it was to cumbersome and when it was fired underground without a silencer its bark was deafening. Making it impossible to hear the enemy.

One of the tunnel rats golden rules was you never fired more than 3 shots underground without reloading, as the VC would know you were out of ammo.

The flashlight was the standard Army issue type and every rat carried one. These were carried in a way so as not to make themselves a nicely illuminated target. If the bulb in the flashlight went it had to be changed. This was practiced so it could be done in pitch darkness by touch alone, and done quickly, lying prone, squatting, or kneeling down. 

Bunker Bomb.

These were made from an ammo can which had a hole drilled in one end. A phosphorus grenade was then taken and unscrewed, the main body of the grenade was placed inside the can. The grenade lever is straightened and fuse is then passed through the drilled hole and screwed back onto the body. Finally the can is filled with napalm or thickened fuel.


Due to the specialised nature of tunnel warfare, priority was placed with ENSURE (Expedited Non-standard Urgent Requirements for Equipment) program for the development of special "Tunnel Exploration kits". Six kits were requested by USARV on the 29th of April 1966, and then passed on to ACTIV (Army Concept Team In Vietnam) on the 7th of August. ACTIV then distributed the six kits, two went to the 1st Inf Div at Di An, a further two were dispatched to the 25th Inf Div at Cu Chi. Of the remaining kits one was given to the 1st Cav at An Khe, whilst the last remaining kit went to the 173rd Airborne Bde at Bien Hoa.

Each kit cost 728 Dollars and consisted of a .38 calibre pistol which was fitted with a suppressor and a spotlight sighting device. This was all carried on a standard pistol belt in a specially designed holster. On the wearers head was a baseball cap which had a miners lamp mounted on it which was switched on and off via a mouth operated bite-switch. At the back of the cap was a bone conduction microphone communication system which was connected to a small ear piece. The power pack for the lamp and a communication wire reel were also hung on the pistol belt, but were situated on the wearers back.

Tests on the exploration kit in Vietnam soon revealed its short comings. The silenced .38 cal pistol was not liked because of its length with the suppressor, and because it lacked balance and was awkward to handle. The special aiming light was found to be unnecessary given the tight confines and short ranges the tunnel rats were operating in. The huge pistol holster was also a failure as it was too big and unwieldy to be used in the tight confines of a tunnel. The head mounted miners lamp fared no better! This was obstructed by the baseball cap's visor and could be shorted out by switch malfunctions rendering it useless. Furthermore the lamp tended to slip down over the wearers eyes. The earpiece part of the communication system was also troublesome as it kept falling out of the wearers ear!

USARV requested 250 tunnel kits on the 21st of March 1967, but because of a mix up in the ordering quantity (500 instead of the original 250) and year end budget problems, immediate funding was slow in coming. Natick labs were not asked to produce the sets until the 30th of September, this situation was further frustrated by problems in the communication equipment for the kits. Eventually the requested 250 sets were delivered to Dover AFB between the 22nd and the 29th of May 1968, and from there immediately flown to Vietnam.

With their patch with it's nonsense Latin motto "Non gratum anus rodentum - Not worth a rats ass" the tunnel rats were among the bravest in Vietnam, doing a job that not many others could, or would care to do.

This I cribbed from several different sources.

These fearless combat engineers descended into the complex Viet Cong tunnels to gather info and disarm bombs — often at the cost of their own lives.

For a soldier during the Vietnam War, one of the most dangerous of obstacles was faced by a select few soldiers known as “tunnel rats.” These unsung heroes of the Vietnam War were American, Australian, and New Zealand soldiers specially trained as combat engineers, who carefully crawled through the cramped Viet Cong underground to perform perilous covert search and destroy missions.

The tunnel rats gently prodded for potentially armed mines in order to disarm them and prayed that they survived with both their legs.

With pistol ready, a G.I. shovels dirt into a tunnel entrance where Viet Cong were believed to be hiding.

Wikimedia Commons

A Network Of Enemy Tunnels

Viet Minh forces initially developed a complex system of underground tunnels to combat the French colonial invasion of Vietnam known as the Cu Chi tunnels. But what began as a fairly rudimentary system of tunnels quickly became a sophisticated labyrinth beneath Vietnam when it was later utilized by the Viet Cong to combat the U.S. and allied forces.

By the onset of the Vietnam war in the 60s, the tunnels included several hospitals, storage facilities, training camps, and barracks. Effective ventilation shafts were later installed which allowed Viet Cong soldiers to remain hidden underground for months at a time.

The tunnels could be destroyed above ground, but often because the tunnels were so complex and snake-like, an above-ground demolition was not enough to dismantle the labyrinth entirely. Someone would have to go down into the tunnels to gather information and better inform their attack. Thus, the tunnel rats came to be.

But the tunnels proved to be an even more mysterious, uncharted area where danger lay around every corner. Besides enemy combatants, the tunnels were decked with booby traps as the Viet Cong knew full well that the American forces would try to use the underground against them.

Viet Cong soldier sits in a tunnel.

Along the tunnels, U-bends had been placed which allowed sections of the tunnels to be flooded and trap a solider. Similarly, entry points were created where poisonous gas could be introduced to kill or render a soldier unconscious.

Less sophisticated traps were also used. Various species of venomous snakes, known to the Vietnamese but not to the outsiders, were dropped into the tunnels.

An American soldier peers into a tunnel’s trap door.

Aside from intentional dangers, there were the natural ones as well. Being underground meant troops were subject to insects, some poisonous like scorpions, and others annoying, like ants. Bats and other creatures used the tunnels as roosts, providing yet another distraction from the task at hand.

The tunnel rats were forced to be creative and often even managed to maneuver around these attacks

Originally called “Tunnel Runners” and later “Ferrets” by the Australian Army, the term eventually morphed into the known “Tunnel Rat.” The rats were comprised of engineering soldiers some of whom were trained at the Australian Army’s School of Military Engineering. Most men were volunteers and tended to be of smaller stature, making it easier to maneuver through the cramped spaces.

But many tunnel rats were devoid of any formal training and though they were sometimes successful in securing intelligence, an enemy hospital, or stores of weapons. However, tunnel rats were responsible for a large portion of weapons successfully seized from the Viet Cong.

Troops often went into the tunnels armed with only an army-issue pistol or revolver, and so the soldiers became ingenious with creating their own weapons. Usually, the weapons of their own devising were sawed-off shotguns and makeshift bayonets. The soldiers also armed themselves with gas masks.

Often when faced with a Viet Cong soldier below ground, tunnel rats had to resort to hand-to-hand combat, as firing a weapon in such a small space could spell disaster for eardrums and the stability of the space around them.

But the tunnel rats’ time underground was to one veteran named Sapper Jim Marrett, “the least of [his] worries.”

In a personal essay for The New York Times, Marrett wrote that as dangerous descending into the tunnels was, “Most of our casualties were aboveground, when we engaged in the other part of our job: finding and disarming mines and booby traps.”

A tunnel rat checks out a possible ventilation shaft.

Marrett reportedly spent weeks in the bush locating and disarming mines, “During that period 36 of us were killed and around 200 were wounded, giving us a casualty rate of 33 percent, high even by Vietnam War standards. One in three of us was either killed or wounded during our tour.”

A soldier pops out of a tunnel trap door to relay information.

Marrett recalled of his company’s tragedies, “…given what we were engaged in, it’s a wonder that number wasn’t higher.”

The tunnel rats were required to use their ingenuity and incredible bravery to fight in an unprecedented form or guerilla warfare the American forces had not yet seen. Indeed, considering the elusive and hidden odds stacked against them, it’s amazing their outcome was not much, much worse.


  1. Good post, and those guys clanked when they walked! Knew one of them years later. He never slept or went into a dark room. ALWAYS had to have the lights on.

    1. Hey Old NFO;

      My Dad told me stories about having to go into the tunnels as part of his job and he absolutely hated going, down the hole. It wasn't for the weak willed.


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